"Farnham Street" seems to be an interesting place where one can read about "...such topics as mental models, decision making, learning, reading, and the art of living." There's self-promotion, yes, and yet there's also self-improvement. And as FS head Shane Parrish said in an interview, "I try to make friends with the eminent dead, like David Foster Wallace, Ben Franklin, Seneca, Cicero, and Marcus Aurelius. There's a lot to be said for also hanging around smart people who are living." From a post last year, "The Difference between Amateurs and Professionals":

Amateurs stop when they achieve something. Professionals understand that the initial achievement is just the beginning.

Amateurs have a goal. Professionals have a process.

Amateurs think they are good at everything. Professionals understand their circles of competence.

Amateurs see feedback and coaching as someone criticizing them as a person. Professionals know they have weak spots and seek out thoughtful criticism.

Amateurs value isolated performance. Think about the receiver who catches the ball once on a difficult throw. Professionals value consistency. Can I catch the ball in the same situation 9 times out of 10?

Amateurs give up at the first sign of trouble and assume they're failures. Professionals see failure as part of the path to growth and mastery.

Amateurs don't have any idea what improves the odds of achieving good outcomes. Professionals do.

Amateurs show up to practice to have fun. Professionals realize that what happens in practice happens in games.

Amateurs focus on identifying their weaknesses and improving them. Professionals focus on their strengths and on finding people who are strong where they are weak.